The pogo transposable element family of Drosophila melanogaster

Abstract

A 190 bp insertion is associated with the white-eosin mutation in Drosophila melanogaster. This insertion is a member of a family of transposable elements, pogo elements, which is of the same class as the P and hobo elements of D. melanogaster. Strains typically have many copies of a 190 bp element, 10-15 elements 1.1-1.5 kb in size and several copies of a 2.1 kb element. The smaller elements all appear to be derived from the largest by single internal deletions so that all elements share terminal sequences. They either always insert at the dinucleotide TA and have perfect 21 bp terminal inverse repeats, or have 22 bp inverse repeats and produce no duplication upon insertion. Analysis by DNA blotting of their distribution and occupancy of insertion sites in different strains suggests that they may be less mobile than P or hobo. The DNA sequence of the largest element has two long open reading frames on one strand which are joined by splicing as indicated by cDNA analysis. RNAs of this strand are made, whose sizes are similar to the major size classes of elements. A protein predicted by the DNA sequence has significant homology with a human centrosomal-associated protein, CENP-B. Homologous sequences were not detected in other Drosophila species, suggesting that this transposable element family may be restricted to D. melanogaster.

Host genome surveillance for retrotransposons by transposon-derived proteins

“…CENP-Bs thought to have originated from transposases encoded by an ancient pogo-like DNA transposon 16,17 could hamper the mobility of LTR retrotransposons (this study). Given that both DNA transposons and LTR retrotransposons are flanked by repetitive DNA structures, and transposases bind to terminal inverted repeats of DNA transposons 2 , it is possible that during evolution a CENP-B precursor acquired the ability to target retrotransposon LTRs, and subsequently was co-opted by the host into its gene repertoire for controlling transposable elements.…”

“…Human CENP-B protein, which facilitates centromere formation by binding to short repeats within centromeric alpha satellite DNA 14,15 , is derived from transposases of pogo DNA transposons 16,17 . CENP-B, highly conserved in mammals, has homologues in other systems 13,18 .…”

Domesticated P Elements in the Drosophila montium Species Subgroup Have a New Function Related to a DNA Binding Property

“…Thus, these proteins could play an important role in two different but non-exclusive ways, firstly by directly regulating the expression of many different euchromatic regions, and secondly by modifying the structure of chromatin. Tudor et al (1992) provided the first example of a class II transposable element protein with a chromatin structure-related function. This was CENP-B, which is one of the centromere proteins of mammals derived from the transposase of the pogo superfamily element.…”

“…This is the only molecular domestication event in this taxon for which the host advantage has been elucidated. In mammals, examples of co-opted transposable elements are well documented, and have been shown to involve the recruitment of either regulatory properties (Hambor et al 1993;Samuelson et al 1996;van de Lagemaat et al 2003) or protein products (Agrawal, et al1998;Tudor et al 1992;Best et al 1996). In these cases, domesticated transposable elements are subjected to selective pressure at the host level, and this allows them to be conserved independently of their transposition activity.…”

msechBari, a new MITE-like element inDrosophila sechelliarelated to theBaritransposon

“…Descriptions in other organisms, such as bacteria (Chen et al, 2008), cyanobacteria , fungi (Xu et al, 2010), silkworms (Han et al, 2010), fish (de Boer et al, 2007) and amphibians (Hikosaka et al, 2011) are also found in the literature, but few occurrences have been reported in the Drosophila genus (Tudor et al, 1992 ;Miller et al, 2000 ;Ortiz et al, 2010). Although numerous MITEs have been identified, the association with autonomous elements is often absent.…”